An Experimental Study of Sprays in Cross Flow Representative of Gas Turbine Engine Secondary Air Systems

The flow in the secondary air system of a gas turbine engine passes over numerous oil supply and scavenge pipes and a fracture in such a pipe will cause a jet of oil to be ejected as a spray. This spray will disperse in the surrounding flow. Accurate and reliable numerical modelling of these sprays presents significant problems due in part to their complexity, but also the lack of experimental data available for model validation. This paper describes the design, manufacture, testing and results from an experimental test rig aimed at spray characterisation. The sprays considered were produced through a round sharp edged nozzle with a 0.57 mm diameter and a length to diameter ratio of 1.61. The spray was introduced normal to the cross flow. Phase Doppler Anemometry was used to determine droplet size and velocity for Weber numbers within the range of 13 < Weg < 580 and Momentum Flux Ratio within the range of 0.8 < q < 136, resulting in 19 different spray fields. Each of these spray fields has been characterised at three axial locations. Contours of droplet size, mass flux distribution, axial droplet velocity and transverse droplet velocity are presented. In addition, a pulsed laser sheet and CCD camera were used to analyse the jet behaviour in terms of break up length and jet trajectory.

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Particulate Monitor for Gas Turbine Cooling Air

Volume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric Power ◽

10.1115/gt2008-51135 ◽

2008 ◽

Author(s):

Richard H. Bunce ◽

Francisco Dovali-Solis ◽

Robert W. Baxter

Keyword(s):

Gas Turbine ◽

Monitoring System ◽

Cooling System ◽

Gas Turbine Engine ◽

Minimum Size ◽

Turbine Engine ◽

Air System ◽

Air Cooler ◽

Secondary Air ◽

Cooling Air

It is important to monitor the quality of the air used in the cooling system of a gas turbine engine. There can be many reasons that particulates smaller than the minimum size removed by typical engine air filters can enter the secondary air system piping in a gas turbine engine system. Siemens has developed a system that provide real time monitoring of particulate concentrations by adapting a commercial electrodynamic devise for use within the confines of the gas turbine secondary air system with provision for a grab sample option to collect samples for laboratory analysis. This on-line monitoring system is functional at typical engine cooling system piping operating pressure and temperature. The system is calibrated for detection of iron oxide particles in the 1 to 100 micrometer range at concentration of from 1 to 50 parts per million mass wet (ppmmw) The electro dynamic device is nominally operable at 800°C. The particulate monitoring system requires special mounting and antenna. This system may be adjusted for other materials, sizes and concentrations. The system and its developmental application are described. The system has been tested and test results are reviewed. The test application was the cooling air piping of a Siemens gas turbine engine. Multiple locations were monitored. The cooling system in this engine incorporates an air cooler and the particulate monitoring system was tested upstream and downstream of the air cooler for temperature contrast. The monitor itself is limited to the piping system and not the engine gas-path.

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Response of a Disk Cavity Flow to Gas Turbine Engine Transients

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2010-22824 ◽

2010 ◽

Cited By ~ 3

Author(s):

David May ◽

John W. Chew

Keyword(s):

Angular Momentum ◽

Gas Turbine ◽

Cross Flow ◽

Gas Turbine Engine ◽

Interactive Effects ◽

System Response ◽

Computationally Efficient ◽

Turbine Engine ◽

Air System ◽

Improved Accuracy

An integral part of the transient operation of a gas turbine engine is the behavior of the engine’s internal air system. It is desirable to model transient air system effects using a computationally efficient method, while accurate representation of these flows may require incorporation of the interactive effects of volume packing and swirl. Thus 1-D methods may need auxiliary relations to account for non-uniformity of properties in the cavity due to swirl or changes in the discharge coefficients of feed and exit holes to account for varying amounts of cross-flow. Consideration of the system response shows that flow spin-up times can be significant, suggesting the inclusion of the conservation of angular momentum in a 1-D volume modeling approach. To clarify the various contributions to the dynamics of these cavities, an axisymmetric rotor-stator disk geometry was modeled using CFD. Results are presented showing a notable effect of rotation. The presence of the rotor increased the time constant by a factor of about 2 for one case studied. The CFD results are compared to 1-D models. The results show improved accuracy of the 1-D model when the conservation of angular momentum is included in the formulation and recommendations for further improvement are made.

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Simplified Ingestion Model Assessment for 1D Gas Turbine Engine Secondary Flow Network

Volume 5B: Heat Transfer ◽

10.1115/gt2017-64388 ◽

2017 ◽

Author(s):

Ashish Negi ◽

A. V. Mirzamoghadam ◽

Sushilkumar Thamke ◽

Balakrishnan Thangavel

Keyword(s):

Gas Turbine ◽

Pressure Profile ◽

Gas Turbine Engine ◽

Model Assessment ◽

Rotating Disc ◽

Turbine Engine ◽

Hot Gas ◽

Secondary Air ◽

Upper Rim ◽

Circumferential Pressure

Modeling of hot gas ingestion in a gas turbine engine is critical because its accuracy directly affects performance as well as turbine durability. In this paper, ASU ingestion test rig data accompanied by its published ingress/egress discharge coefficients (Cdi and Cde , formulation) are used to propose a simplified 1D ingestion model embedded in the secondary air system software (Network). The proposed externally induced ingress model includes separate boundary nodes with equal static pressure in the annulus hub, and distinct circumferential pressure variation in the form of normalized annulus pressure at the hub (P1 – P1avg)/(P1max – P1min). The corresponding Cdi and Cde for the engine conditions are scaled based on rig-to-engine non-dimensional minimum purge, Cwmin where engine Cwmin uses the actual (P1 – P1avg)/(P1max – P1min) derived from previously published CFD data along with the effective rim-seal overlap clearance. The vane pitch integrated driving pressure difference at the hub for the ingestion used in the orifice model comes from an embedded saw-tooth assumption on the circumferential pressure profile. Recirculation of ingested hot gas from the upper rim cavity to the lower wheel space is considered by comparing the supplied purge flow to the rotating disc entrainment requirement. The proposed model is compared with another model based on constant Cdi / Cde ratio of 0.14 published by the University of Bath. Engine test data from a previously published engine configuration is used to assess the appropriate model for engine. The probability of failure in violating the lower rim cavity sealing effectiveness limit based on analysis of variation (AOV) was conducted under both formulations and the results are presented.

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A CFD-BASED STEADY-STATE TESTING METHODOLOGY FOR A COOLED-COOLING AIR HEAT EXCHANGER IN THE SECONDARY AIR SYSTEM OF AN AERO GAS-TURBINE ENGINE

Journal of computational fluids engineering ◽

10.6112/kscfe.2020.25.1.072 ◽

2020 ◽

Vol 25 (1) ◽

pp. 72-81

Author(s):

Alberto Mucci ◽

Foster Kwame Kholi ◽

Hariharan Kallath ◽

Thierry Sibilli ◽

June Kee Min

Keyword(s):

Steady State ◽

Heat Exchanger ◽

Gas Turbine ◽

Gas Turbine Engine ◽

State Testing ◽

Turbine Engine ◽

Testing Methodology ◽

Air System ◽

Secondary Air ◽

Cooling Air

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Characterizing Compressor Rotor Unclamp in a Gas Turbine Engine

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2012-68882 ◽

2012 ◽

Cited By ~ 1

Author(s):

Cory Alban ◽

Masha Tolstykh ◽

Devin Hilty ◽

Andrew Bollman

Keyword(s):

Gas Turbine ◽

Robust Design ◽

Extended Period ◽

Gas Turbine Engine ◽

Tip Clearance ◽

Transient Condition ◽

Element Analysis ◽

Turbine Engine ◽

Compressor Rotor ◽

Secondary Air

In the aerospace industry, many gas turbine compressors rely on a tie bolt to mechanically hold together all rotating components in the compressor rotor. Maintaining this clamp load is essential to the performance of the engine. In the event of an unclamp, the engine will experience a reduction in tip clearance due to a change in rotational dynamics; increased temperatures and pressures in secondary air systems; and a decrease in critical component life. Accordingly, designers must be aware of the variables effecting compressor rotor clamp loads observed for component assembly and operational missions. During testing, an axial gas turbine engine unexpectedly experienced a compressor rotor unclamp which led to an increase in turbine temperature and front sump buffer air temperature and pressure. Further investigation revealed a thermal expansion mismatch between the tie bolt and inner gas path rim during a specific transient condition. Because of this thermal effect, the rotor will experience an unclamped condition which will result in ingesting compressor discharge air into the drum. The compressor rotor will remain unclamped until the engine is operated at a lower power setting or shut down for an extended period. This paper documents and explains the transient condition at which the engine experienced unclamp through review of test data, characterizes the design space around the tie bolt by using heat transfer and structural finite element analysis codes, and shows how robust design tools were used to find an optimized solution that eliminated the risk of thermally driven unclamp through robust design and assembly choices.

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A Development of the Fuel Atomizing Device Utilizing High Rotational Speed

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/81-gt-180 ◽

1981 ◽

Cited By ~ 2

Author(s):

T. Morishita

Keyword(s):

Gas Turbine ◽

Droplet Size ◽

Rotational Speed ◽

Liquid Fuel ◽

Tangential Velocity ◽

Gas Turbine Engine ◽

High Rotational Speed ◽

Turbine Engine ◽

The Mean ◽

Atomization Characteristics

A fuel atomizing device was developed for a combustor of a small gas turbine engine. The device is a rotary atomizer in which liquid fuel is supplied through a stationary nozzle onto a specially shaped disc rotating with a high tangential velocity (over 200 m/sec). The rotary atomizer has shown remarkably good atomization characteristics when used in the engine. The mean droplet size of the atomizer is explained by the following equation for water: SMD = 0.033 • U−0.7 • Q0.2 • D0.3. The SMD for fuel can be evaluated by the correlation of: SMD∞(σ/ρ)0.5. The performance together with its configurations will be discussed in detail.

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